Automatic thread cutting mechanism for button sewing machines



Dec. 12, 1967 H. E. OWENS 3,357,387

AUTOMATIC THREAD CUTTING MECHANISM FOR BUTTON SEWING MACHINES ATTOR NE YDec. 12, 1967 H E. OWENS 3,357,387

AUTOMATlC I'HRAD CUTTING MECHANISM FOR BUTTON SEWING MACHINES Filed DeC.22, 1965 2 Sheets-Sheet E 55k 57\ 5% IMM/A/ FIGB INVENTOR HORACE E,OWENS ATTORNEY United States Patent Otice 3,357,387 Patented Dec. 12,1967 3,357,387 AUTOMATIC THREAD CUTTING MECHANISM FOR BUTTON SEWINGMACHINES Horace E. Owens, Owings, S.C., assigner to Her MajestyUnderwear Company, Mauldin, S.C., a corporation of South CarolinaFiled'Dec. 22, 1965, Ser. No. 515,612 9` Claims. (Cl. 112252) Thisinvention relates to a thread. cutting mechanism for sewing machines.

Themain objective of the invention is to provide a simplified,economical, automaticthread cutting attachment for a certain class fofbutt-on sewing'machines which will cut the ythread cleanly uponcompletion of each button sewing cycle. The mechanism is particularlyadaptable to a shank button .sewing machine designated Class 175-'62 inaninstruction booklet for Singer Sewing Machines, 1958 edition, by theSinger Manufacturing Company; The particular button sewing machine isentirely conventional and is well-known in the art.`

Another object ofthe invention is to provide an automatic thread cuttingattachment for the above class of machine which takes advantage of themovement of the sewing machine stop motion for directly controlling thecycle of operation of the invention. This greatly simplifies theinvention mechanism and renders it substantially foolproof in its timingand automatic cycle of operation and results in the minimum possiblenumber of parts for the actual attachment.

Still. another object is to provide an automatic thread cuttingattachment which is rugged and durable and which requires no alterationof the basic sewing machine structure or repositioning of its operatingcomponents and no interference with the button sewing cycle ofoperation.

Other objects and advantages of the invention will become apparentduring'the course of the following detailed description.

In the accompanying drawings forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

FIGURE 1 is a fragmentary plan view of a shank button sewing machine,partly in cross section, having the invention thread cutting mechanismmounted thereon in one operative position;

FIGURE 2 is a similar view showing the thread cutting mechanism in theactive or cutting position;

FIGURE 3 is an enlarged fragmentary side elevational View of the threadcutting mechanism;

FIGURE 4 is an enlarged fragmentary end elevation, partly in section, of)the sewing machine and invention mechanism showing the relativeposition of parts at the completion of a button sewing cycle;

FIGURE 5 is a similar view of the same parts at the beginning of thebutton sewing cycle; and

FIGURE 6 is a fragmentary vertical section taken on line 6 -6 of FIGURE2.

In the drawings, wherein for the purpose of illustration is shown apreferred embodiment of the invention, the numeral 10 designatesgenerally a conventional shank button sewing machine of the type knownin the art as a Singer Model No. 17562 machine. This machine includes awork surface or plate 11 over which the cloth, not shown, is positionedto have shank buttons 12 sewn thereonby the well-known zig-zag needlemechanism. The shank buttons are positioned on edge, as shown in FIGUREl, in a special anvil or support 13 for this purpose, also of a known,conventional construction.

The sewing machine has a main drive shaft 14 upon which is mounted astop dog 15 which operates in conjunction'with a cushion spring holder16 mounted on a machine rock shaft 17 and carrying. a stop dogcushioning spring 18 projecting therefrom asA shown inthe drawings.Tlie'elements16, 17 and 18, yalongwith the stop dog 15, are allconventionalparts. ofthe machine stop motion' which are cycled. andkoperated automatically,

The automatic thread cutting mechanismv forming the direct subjectmatter. ofthe invention comprises, an, elongated bar 19 havingalongitudinal groove 20 in itstop face and serving as a fixed bedorfguideforatifr elongated carriage member 21 which` engages slidably withinthe` groove 20 and extends for its entire; length, The. bar 19 whichforms the supporting body. portion of: the mechanism isA attached to one'side of they machine based-.2 2A by, Vscrews 2.3- or` the ylike atspaced points. 'fhecarriage member-21- which is in effectA a slideincludes. forward laterallyr enlarged head portion 24 integraltherewithhaving shoulders 25 adapted to engage the forwardenclfof4 thebari'19fso as to positively limitl Ythe rearward` movementoftthecfaririage member. The carriage member '21, is resilientlyfbialsed aretracted or inactive position, as shown FIGURE 1, by a carriage returnspringy 2%6fhavin'g its forwardfend, choredv at 27 to the carriagemember! and its rear-endsimilarly anchored at 28 to a 'bracket 29tixedlyl secured, at 3.0 to therear portion of. bar 19, In addition toanchoring the spring 2,6,v the. stationaryy bracket 2 9*V aids-Vinfretaining the carriage memberor slide 21 in thes liallovvgrooveulll,y A further retainer plate is providedffor this] purpose onthe `bar 19 near. the forward engll ofI the same. Thel bracket 29 alsolimits` the forward movement'ofcarriage member 21 by contact with anupstanding rigid 32 formed integrally on thel rear 'end' thereof.In"normal operation forI thread cutting, "the extent of "forward moveIment of the carriage member l21, is such that the lugl 32 does not quitemake contact with the bracke`t`2l9'. VNef/,ertheless, this bracketywouldrestrict excessive forward movement of the carriage member.

The forward, head 24 is provided with al longitudinal slot 33, allowingthe adjustable connectionn ofal horizontal extension arm 34 tothecarriage member 21, as 1indicated at 35. The extension arm 34 projectslaterally of the carriage member and closely Aoverlies theV machine worksurface 11. The extension arm. 34,is thus mounted. bodily upon thecarriage member 21 and reciprocatestherewith.

A reciprocatory thread cuttingblade. or knife 3.6 operates slidably uponthe anvil surface 13. beneath agrooved hold-down and guide element 37xedly. securedfto the member 13. The leading end. 3.8 of;blade 36 issuitably beveled to form a thread cutting edge. The blade. is adapted tooperate beneath the cloth, not shown, to cut olf the thread cleanlyclose to the buttonshankr 39 after the sewing operation is completed.The rear end` of blade 36 carries an upstanding pin 4t) which isreceivedby a slot y4,1. in the extension arm 34 so. that the latter, maydrive the blade36 smoothly.l andwithout binding. It will be understoodthat the elements 2,1, 34 and. 36`recipro.- cate as a unit and haverectilinear motion imparted thereto along the guide slot520.

Fixedly anchored withinan opening 4,2inrtherear end of bar 19 is a pinor` shaft 43held in place by a set screw 44 or thek like. The shaft,4 43projects for a considerable distance beyond the rear end of the bar 19and has adepending positioner arm 45 rigidly secured thereto as,by a setscrew 4,6. The elements-@and t5-are therefore, both rigidwith thestationary bar 19,l

Between the pos'itionerv arrnk45.andtherearendof bar 19 a sleeve 47 isrotatablyy mounteduponthe shaft" 43, andthissleeve directly carries aplunger` guide 43, which may be integral therewith orl weldedthereto.Ther,lplunger guide 48 is on the top of sleeve 47,- asv'shown, and..yprojects laterallybeyond. theinner side thereof. and across the-back ofthe machine. base22, FIGUREAQAbloclclike cam actuator 49 is arrangedwithin a recessed portion of the plunger guide 48 and is pivoted theretofor horizontal turning movement thereon by a suitable pivot element 50arranged near one corner of the cam actuator. As shown in FIGURES 1 and2, the cam actuator 49 is square and when it is in the inactiveposition, FIG- URE l, one of its straight sides 51 abuts the edge of therecess in which the actuator is seated so that it will turn no furtherin the counter-clockwise direction, as viewed in FIGURE 1. The camactuator 49 is resiliently biased to this inactive position by a returnspring `52 having one of its Vends anchored to the cam actuator and itsother' end similarly anchored to the plunger guide 48.

The kforward edge 53 of the cam actuator 49 which directly engages thelug 32 of carriage member 21 is normally spaced slightly therefrom whilein the inactive position, as indicated at 54 in FIGURE 3. The camactuator 49 is caused to turn to the active position in FIGURE 2 by aplunger 55 mounted slidably within a bore of the plunger guide 48 andhaving its leading end directly contacting the edge 51 of the camactuator 49. The pin element 56, FIGURE 6, which serves to anchor thespring 52 to the guide 48, may also pass through a notch 57 formed inthe plunger 55,l so as to limit positively the reciprocatory movement ofthe plunger upon the guide 48.

It may now be understood that the entire guide 48, plunger 55 and camactuator `49 are all bodily mounted upon and turnable with the sleeve 47upon the axis of shaft 43. The freely rotatably plunger guide 48 andassociated elements rests freely upon and is supported by the cushionspring holder 16, as best shown in FIGURE 4, and this constitutes animportant feature of the vinvention and its operation, to be furtherdescribed. A diagonal positioner spring 58 interconnecting theguide 48and the positioner arm 45, as shown at 59, serves to resiliently holdthe guide in rm contact with the spring holder 16 at all times. When thespring holder 16 turns in either direction with the rocker shaft 17, theplunger guide 48 and associated elements will turn automaticallytherewith, and the spring 58 will maintain contact between the parts 4Sand ,16, as shown.

The cycle of operation of the thread cutting mechanism above-describedin conjunction with the sewing machine stop motion is as follows:`

When the sewing machine is engaged in a conventional manner to beginIthe button sewing cycle, the machine stop dog cushioning spring holder16 automatically rotates away from the revolving stop dog which turnswith the main drive shaft 14. This ysituation is shown in FIGURE 5. Whenthis occurs, the holder 16 will lift and carry the plunger -guide 48,plunger 55 and all associated parts away from the stop dog and out ofits path of rotation during the sewing of the Button onto the cloth.

As the normal sewing cycle is completed, the cushion spring holder 16will return automatically to its active machine stopping position shownin FIGURE 4 and this is conventional in the sewing machine. This allowsthe positioner spring 58 to` pull the plunger guide 48 down to theactive approximately level position shown in FIG- URE 4. At this time,both the plunger 55 and the cushion spring 18 are in the path ofmovement of the rotating stop dogf15.

As the stop dog 15 moves into the stop position and sli-ghtly shortthereof, it contacts plunger 55, FIGURE 4, causing the plunger to shiftaxially toward the cam actuator 49 and turning the cam actuator, asshown in FIGURE 2, to cause shifting of` the carriage member 21 andblade 36 to the thread severing position where the thread is cleanlysevered close to the button shank.

'I'he plunger 55 absorbs the initial impact of stop dog 15 and actuallyaids in stopping the machine. However, continued slight'movemeut of thestop dog after engaging the plunger brings the stop dog into contactwith the cushioning spring 18 and completes the stopping of the shaft 14and the machine. Following this, the compressed spring 18 expands to itsrelaxed position and normal length pushing back the stop dog 15 slightlyand allowing the cam actuator 49 to return to the inactive position inFIGURE l under influence of the spring 52. This also moves the plunger5S to its retracted or inactive position. At this time, the carriagereturny spring 26 automatically withdraws cutting blade 36 from Vthethread and returns the blade, arm 34 and carriage member 21 to the fullyretracted position, thus completing the sewing and thread cutting cycleand preconditioning the parts for the next cycle of operation, where theholder 16 again moves the guide 48 and associated elements clear of thepath of movement of the dog 15, as the machine starts up.

It is now clear that a highly simplified positive acting automaticthread cutter has been provided on the shark button sewing machine whichis operated directly by the machine stop motion in such a mannerthat thethread is cut at precisely the right time, namely, at the end of thecutitng cycle. Also, the mechanism in conjunction with the stop ymotionconditions itself automatically for each succeeding cycle of operation,as explained.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as a preferred example of the same, and thatvarious changes in the shape, size and arrangement of parts may be`resorted to, without departing from the spirit of the invention orscope of the subjoined claims.

I claim:

1. A thread cutting mechanism for u button sewing r machine of the classhaving a rotating stop dog and a coacting cushioning part movablecyclically into the path of travel of the stop dog and clear of suchpath of travel, said mechanism comprising a supporting body portionattachable to the body of the sewing machine, a thread cutter devicemovably engaging said body portion and shiftable thereon toward and awayfrom threadcutting positions, and an actuator means for the threadcutter device movably mounted upon the supporting body portion and beingengaged with and supported by said cushioning part and shiftable withsuch part cyclically into the path of travel of the stop dog so that thestop dog may directly engage said actuator means and operate said cutterdevice to cut the button sewing thread.

2. The invention as defined by claim 1, and wherein said cutter deviceis a reciprocating cutter on the supporting body portion and saidactuator means comprises a member pivoted to the body portion andadapted to rest upon the cushioning part, a plunger having guidedengagement with said member and adapted to be engaged directly by saiddog, and a pivoted cam actuator carried by said member and movablebodily therewith and adapted to engage said reciprocating cutter.

3. A thread cutting mechanism for a button sewing machine of the classhaving a rotating machine stop dog and a coacting stop part which swingscyclically into the path of movement of the stop dog and clear of saidpath of movement, said mechanism comprising a guiding and supportingmember adapted to be rigidly secured to one side of the sewing machinebase, a reciprocatory slide on said member, resilient means biasing saidslide to a retracted position, a thread cutter element carried by theslide and positioned for direct engagement with the thread to cut thethread when the slide is extended on said guiding and supporting member,a plunger guide body pivotally mounted upon one end of the guiding andsupporting member and adapted to contact and. rest upon said coactingstop part and to swing therewith, resilient means connected with theplunger guide body and holding it in Contact with the coacting stoppart, a reciprocatory plunger on said guide body and adapted to direct-1y engage said stop dog when in the path of movement thereof, a pivotedactuator part on the guide body and shiftable by said plunger againstsaid slide to move the same in a thread cutting direction, and resilientmeans connected with said actuator part and urging the same toward aninactive position with said plunger.

4. The invention as dened by claim 3, and wherein said guiding andsupporting member is an elongated bar having a longitudinal groove, saidslide engaging within said groove and extending longitudinallytherethrough, a lateral extension arm on the forward end of said slide,and said thread cutter element offset from said slide and connected withsaid extension arm.

5. The invention as defined by claim 3, and a shaft extension on therear end of the guiding and supporting member, a sleeve rotatablymounted on the shaft eX- tension and bodily carrying said plunger guidebody, a depending member on the shaft extension, and a retractile springinterconnecting the depending member and said plunger guide body to holdthe same in contact with said coacting stop part and allowing theplunger guide body to swing with the coacting stop part.

6. The invention as defined by claim 3, and wherein said pivotedactuator part is a block-like element on the top of the plunger guidebody, said guide body having a recess receiving said actuator part, anda lug on said reciprocatory slide positioned for engagement with oneedge of the actuator part when the same is turned by said plunger.

7. In a button sewing machine of the class having a rotating stop dogand a coacting pivoted stop part which swings cyclically into the pathof movement of the' stop dog and clear of said path, the combinationwith said coacting stop part of a pivoted guide device on said machineresting upon and supported by the coacting stop part, resilient meansholding the guide device in contact with the coacting stop part, movableactuator means on said guide device adapted to be operated by thev stopdog when said coacting stop part swings into the path of movement `ofthe stop dog, and movable thread cutter means on said machine operatedby said actuator means in response to operation thereof by the stop dogimmediately prior to the stopping of the machine by engagement of thestop dog with the coacting stop part.

8. The invention as dened by claim 7, and wherein the coacting stop partincludes a cushioning spring for the stop dog and said actuator meansincludes a plunger extending slightly in advance of the cushioningspring to engage with the stop dog prior to engagement of the dog withsaid spring.

9. The invention as defined by claim 7, and a common support member onsaid machine for the thread cutter means and pivoted guide device.

References Cited UNITED STATES PATENTS 1,841,102 1/1932 Field 112-2522,509,619 5/1950 Vollman 112-252 3,267,892 8/1966 Maschmann et al.112--252 X PATRICK D. LAWSON, Primary Examiner.

I. R. BOLER, Assistant Examiner.

1. A THREAD CUTTING MECHANISM FOR A BUTTON SEWING MACHINE OF THE CLASSHAVING A ROTATING STOP DOG AND A COACTING CUSHIONING PART MOVABLECYCLICALLY INTO THE PATH OF TRAVEL OF THE STOP DOG AND CLEAR OF SUCHPATH OF TRAVEL SAID MECHANISM COMPRISING A SUPPORTING BODY PORTIONATTACHABLE TO THE BODY OF THE SEWING MACHINE, A THREAD CUTTER DEVICEMOVABLY ENGAGING SAID BODY PORTION AND SHIFTABLE THEREON TOWARD AND AWAYFROM THREAD CUTTING POSTIONS, AND AN ACUTATOR MEANS FOR THE THREADCUTTER DEVICE MOVABLY MOUNTED UPON THE SUPPORTING BODY PORTION AND BEINGENGAGED WITH AND SUPPORTED BY SAID CUSHIONING PART AND SHIFTABLE WITHSUCH PART CYCLICALLY INTO THE PATH OF TRAVEL OF THE STOP DOG SO THAT THESTOP DOG MAY DIRECTLY ENGAGE SAID ACTUATOR MEANS AND OPERATE SAID CUTTERDEVICE TO CUT THE BUTTON SEWING THREAD.